I think Supergirl was really good. I did a whole review thread about what I liked, but let me tell you something: if the movie was "bad", that still wouldn't mean that the creatives who made it "failed". The fact that movies get made at all is sort of a miracle. It's such a complex process involving so many people!
To me, a movie is a creative failure when it is an assembly-line corporate product that was loved by no one who helped make it. THAT is a fucking tragedy.